Polyisocyanurate foams are well known. Such foams, when used for floral foam, must be able to hold the flower stems firmly. If the foam recovery is too great and the foam is too flexible, the stems are not held but are pushed out of the foam support. Jabs, et al., U.S. Pat. No. 3,873,476, describes a hydrophilic polyurethane foam which is suitable for use as a substrate for cut flowers. The diisocyanate is partly biuretized by reacting the diisocyanates with water, before mixing with a polyester polyol.
Smith, U.S. Pat. No. 4,525,490, describes a flexible open cell polyurethane foam composition. Hopkins, U.S. Pat. No. 4,036,792, describes polyisocyanurate foams prepared using a cocatalyst system. Polyisocyanurate foams are also described in Moss et al. U.S. Pat. No. 4,169,921, Skowronski, et al., U.S. Pat. No. 4,311,801, Bernard et al., U.S. Pat. No. 4,405,725, Ashida et al., U.S. Pat. No. 4,514,525, Tideswell et al., 4,544,679, Soukup, et al., U.S. Pat. No. 4,710,521 and Okina, U.S. Pat. No. 4,952,358.
Wells, U.S. Pat. No. 3,993,608 describes poly (urethaneisocyanurate) foams containing hollow glass spheres. Rigid isocyanurate polyurethane foams and methods for preparing these foams are also described in Biranowski, et al., U.S. Pat. No. 4,271,273. Ohashi et al., U.S. Pat. No. 4,189,541 describes a method for producing heat resistant and flame resistant polyisocyanurate foams using little or no organosilicone surfactant. Likewise, Austin, et al., U.S. Pat. No. 4,067,833, also describes urethane modified polyisocyanurate foams.